Thursday, May 19, 2011
A prostate-specific antigen (PSA) test taken for the first time between the ages of 44 and 50 can predict the likelihood that a man will die from prostate cancer over the next 25 to 30 years, according to researchers at Memorial Sloan Kettering Cancer Center. The findings, which will be presented as part of the 2011 American Society of Clinical Oncology (ASCO) annual meeting, suggest that more than half of men could forego annual PSA testing and have just three PSA tests in their lifetime, the first one between the ages of 44 and 50. Men between the ages of 44 and 50 with higher PSA levels are at high risk for aggressive prostate cancer and should continue to receive PSA tests and screening as necessary, according to the authors.
Prostate cancer is the most common cancer among American men and the second leading cause of cancer deaths in men, according to the American Cancer Society. While PSA testing is recommended for the early detection of prostate cancer, it is also associated with a high rate of overdiagnosis and overtreatment, a particular problem because treatment for prostate cancer is associated with erectile and urinary dysfunction.
“This research helps us distinguish between those men who may benefit from regular PSA screening for prostate cancer and those men who may not need to be screened so frequently,” said lead author Hans Lilja, MD, PhD, a clinical chemist at Memorial Sloan Kettering with joint appointments in the Departments of Laboratory Medicine, Surgery, and Medicine. “Instead of testing all men each year or every two years, screening and surveillance efforts can be focused on early detection of prostate cancer in those men who are found to be at high risk of death from the disease.”
The researchers analyzed archived blood samples from 12,090 men between the ages of 44 and 50 who provided blood between 1974 and 1986, and repeat samples from 4,999 of those men six years later as part of the Malmö Preventive Project in Sweden. Blood samples from 1,167 60-year-old men involved in the Malmö project were also included. All of the men who provided blood for the samples had never received any screening for prostate cancer.
Analyzing each of the three samples — men ages 44 to 50, 51 to 55, and age 60 — the researchers determined median PSA levels to serve as baselines distinguishing between low risk and high risk for developing aggressive prostate cancer. The study found that a PSA level below the median between the ages of 44 and 50 was associated with a very low risk of prostate cancer death or metastases within 15 years, although it did not rule out lifetime risk. By age 60, the risk decreased significantly down to 0.5 percent for those men with a PSA level below the median.
Currently, the American Cancer Society recommends that men discuss prostate cancer screening with their doctor at age 50 to determine whether it’s appropriate for them. This study indicates a new screening interval, suggesting that men start that discussion at an earlier age and receive their first PSA test between the ages of 44 and 50. If the men are found to be at low risk, they do not need to undergo frequent PSA tests, according to the researchers. Instead, the study suggests that these men should receive a second PSA test between the ages of 51 and 55, and if their PSA levels are still found to be low, they should receive their final PSA test at age 60.
“This study supports other research showing that most men do not need annual PSA screenings,” said Peter Scardino, MD, Chair of the Department of Surgery at Memorial Sloan Kettering. “If men received their first PSA test at an earlier age, between 44 and 50, those with a low risk for developing a dangerous cancer could then be tested less frequently, reducing costs and the chances of overdiagnosis and overtreatment of indolent cancers.”
This investigation was supported by the National Cancer Institute, the Swedish Cancer Society, the Swedish Research Council, the Sidney Kimmel Center for Prostate and Urologic Cancers, David H. Koch through the Prostate Cancer Foundation, and Fundación Federico SA.
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